This invention is concerned with wastewater purification for disposal purposes and with the reclamation of waste oils contained therein. In particular, it is concerned with industrial wastewaters which contain dissolved and emulsified oils, such as water soluble oils, cutting oils, hydraulic oils, drawing compounds and the like.
Treatment of such wastewaters for disposal has generally been accomplished by forming an oil gathering or oil adsorbing floc in the water (sometimes referred to as chemical coagulation).
One of the more conventional coagulation or flocculation techniques is the one known as the acid-alum-lime sedimentation method. In it, the wastewater to be treated is usually acidified to adjust its pH to about 3.5. Free oils are skimmed from its surface. Alum is added, followed by additions of lime to adjust the pH to about 6-8. Floc formation (aluminum hydroxide) and coagulation occurs. The emulsion is broken and oil is adsorbed from the water by the floc. If it is desired to reclaim the oil, the oil-laden floc is separated from the water and the oil may be removed therefrom. It is an object of this invention to improve such coagulation and flocculation techniques by providing for the reuse or recycling of substantial amounts of the floc forming constituent, such as the alum mentioned in the foregoing example, to effect both cost and chemical savings.
It is an object to effect the foregoing in facilites already using flocculation techniques with only minor equipment changes being required.
It is an overall object of this invention to improve treatment techniques and to decrease costs in reclaiming emulsified oils from industrial wastewaters.
These and other objects will become apparent from the following description of the invention.